大变形有效应力分析退化为总应力分析的新方法

传统方法在将有效应力分析向总应力分析退化时，一般采用将所有节点的孔压置为0的办法，这相当于对所有节点引入0压边界条件而影响了程序的通用性。将广义Terzaghi有效应力原理引入大变形固结理论中，并推导了其增量有限元方程。提出将广义有效应力系数置为0的新方法，实现了大变形有效应力分析向总应力分析的退化。新方法概念清晰，操作简单，不需要修改边界条件，可增强大变形有效应力分析程序的通用性。通过算例分析，证明了新方法的有效性。应用中可分别将广义有效应力系数置为1和0，对同一模型经过2次运算后，可对任意点在任意加荷条件下的固结沉降、最终沉降、固结度等指标进行准确评估，为工程设计和施工控制提供有效的分析手段。

A new method for reducing large deformation effective stress analysis to total stress analysis

Effective stress analysis (ESA) is reduced to total stress analysis (TSA) usually by means of setting pore-water pressures at all nodes as zero, which is similar to introduce zero-pressure boundary condition (BC) and therefore decreases the versatility of programs. Terzaghi’s general effective stress principle is introduced into large deformation consolidation theory in this paper, and the corresponding incremental finite element formulations are derived. By means of setting general effective stress coefficient (GESC) as zero, a new method for reducing large deformation ESA to TSA is proposed. The presented method can be easily used without modifying any BC at all, as well as a clear concept and the increase of versatility of large deformation program of ESA. A case study was carried out; and the results show that the proposed method is as effective as expected. Setting GESC with the value of 1 and 0 respectively in the same model, the precise results could be obtained for the prediction of consolidation settlement, ultimate settlement and the degree of consolidation at any point under arbitrary load. The presented method provides an efficient tool for engineering design and construction control.